System and method for flameless thermal oxidation at optimized equivalance ratios

ABSTRACT

A diptube assembly for a flameless thermal oxidizer having a matrix bed of media is provided. The diptube assembly comprises a fuel conduit at least partially positioned within the matrix bed for delivering fuel. An oxidizing agent conduit is at least partially positioned within the matrix bed for delivering oxidizing agents, wherein the oxidizing agent conduit is separate from the fuel conduit. At least one mixing conduit is positioned within the matrix bed and configured to receive fuel from the fuel conduit and the oxidizing agent from the oxidizing agent conduit. The mixing conduit is positioned to deliver the combination of fuel and oxidizing agents into the matrix bed of media.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase application of PCTInternational Application No. PCT/US2009/036724, filed Mar. 11, 2009,which claims priority to U.S. Provisional Patent Application No.61/035,589, filed on Mar. 11, 2008, the contents of such applicationsbeing incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a flameless thermal oxidizer configuredfor flameless thermal oxidation at optimized equivalence ratios, and amethod of flameless thermal oxidation at optimized equivalence ratios.

BACKGROUND OF THE INVENTION

Many industries, such as the chemical, pharmaceutical, oil refinery,power utility, and electronic industry react chemicals at hightemperatures, for example about 1000 degrees Fahrenheit. The terms“react” or “reaction” refer to any endothermic or exothermic chemicalreaction, such as the vaporization, synthesis, oxidation, or reductionof a chemical. For example, and though a wide variety of applicationsexist for vaporization, it is often desirable to vaporize liquid naturalgas (LNG) so that it can be handled and distributed as a fuel source.Alternatively, chemicals and fume streams may be safely destroyedthrough oxidation by converting the chemical to reaction products, suchas carbon dioxide and water. Thermal oxidation is a process wherebysolvents and hydrocarbons combine with oxygen to form water and carbondioxide. The products of reaction from the original mixture of solventscan thereafter be safely discharged to the atmosphere.

One type of apparatus that can be used to facilitate thermal oxidationis a flameless thermal oxidizer (FTO). The reaction is referred to as‘flameless’ because the FTO permits the reaction of the process gasstream to occur in the absence of a flame. The flameless thermaloxidizer may be utilized, for example, to treat organic vent gasesreleased from organic synthesis reactors and similar hydrocarbon off-gascontrol applications, to vaporize liquid natural gas, or to synthesizewaste hydrocarbon gas or natural gas feedstock through a non-catalytic,partial oxidation process. Flameless thermal oxidizers are described,for example, in U.S. Pat. No. 6,015,540 to McAdams et al., which isincorporated herein by reference in its entirety.

In the interests of efficiency and/or safety, there exists a need tofurther develop and improve FTO's to facilitate a substantially completeoxidization reaction of a fume stream with reduced risk of flashback,while reducing operational costs and/or improving the available capacityof the vessel.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a diptube assembly for aflameless thermal oxidizer having a matrix bed of media is provided. Thediptube assembly comprises a fuel conduit at least partially positionedwithin the matrix bed for delivering fuel. An oxidizing agent conduit isat least partially positioned within the matrix bed for deliveringoxidizing agents. The oxidizing agent conduit is separate from the fuelconduit. At least one mixing conduit is positioned within the matrix bedand configured to receive fuel from the fuel conduit and the oxidizingagent from the oxidizing agent conduit. The mixing conduit is positionedto deliver the combination of fuel and oxidizing agents into the matrixbed of media.

According to another aspect of the invention, a diptube assemblycomprises a fuel conduit for carrying fuel at least partially positionedwithin the matrix bed. A fuel plenum is positioned within the matrix bedand configured to receive fuel from the fuel conduit. The diptubeassembly further comprises an oxidizing agent conduit for deliveringoxidizing agents into at least one mixing conduit. At least a portion ofthe mixing conduit is positioned within the fuel plenum. The portion ofthe mixing conduit includes at least one aperture formed in a surfacethereof, wherein fuel from the fuel plenum is delivered into the mixingconduit through the aperture. A combination of fuel and oxidizing agentsare delivered through the mixing conduit into the matrix bed of media ofthe flameless thermal oxidizer.

According to still another aspect of the invention, a flameless thermaloxidizer (FTO) is provided. The FTO comprises a vessel, a matrix bed ofmedia contained within an interior of the vessel, and a diptube assemblyat least partially positioned within the matrix bed. The diptubeassembly includes a fuel conduit for carrying fuel that is at leastpartially positioned within the matrix bed, an oxidizing agent conduitfor carrying oxidizing agents that is at least partially positionedwithin the matrix bed, and at least one mixing conduit that is at leastpartially positioned within the matrix bed that is configured to receiveand combine fuel from the fuel conduit and oxidizing agents from theoxidizing agent conduit and to deliver the combination of fuel andoxidizing agents into the matrix bed of media.

According to still another aspect of the invention, a method ofdelivering fuel and oxidizing agents into the vessel includes the stepsof distributing fuel through the fuel conduit; distributing oxidizingagents through the mixing conduit; and combining the fuel and theoxidizing agent in a mixing conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawing. It is emphasizedthat, according to common practice, the various features of the drawingmay not be to scale. On the contrary, the dimensions of the variousfeatures may be arbitrarily expanded or reduced for clarity. Included inthe drawing are the following figures:

FIG. 1 is a schematic cross-sectional view of a flameless thermaloxidizer (FTO); and

FIG. 2 is a schematic cross-sectional view of an FTO including a diptubeassembly according to an exemplary embodiment of the invention;

FIG. 3 is a detailed cross-sectional view of the diptube assembly ofFIG. 2;

FIG. 4 is a top plan view of the diptube assembly taken along the lines4-4 of FIG. 2;

FIG. 5 is a detailed cross-sectional view of a mixing conduit of FIG. 3according to an exemplary embodiment of the invention;

FIG. 6A is a detailed cross-sectional view of the mixing conduit of FIG.5 taken along the lines 6-6; and

FIG. 6B is another detailed cross-sectional view of a mixing conduitaccording to another exemplary embodiment of the invention, wherein theapertures of the mixing tube are disposed at alternate positions.

DETAILED DESCRIPTION OF THE INVENTION

The invention will next be illustrated with reference to the figures.Such figures are intended to be illustrative rather than limiting andare included herewith to facilitate explanation of the presentinvention. In the figures, like items numbers refer to like elementsthroughout.

FIG. 1 depicts a flameless thermal oxidizer (FTO) 40 shownschematically. The FTO operates by thermally reacting a process gasstream within a matrix bed of porous inert media (PIM). Morespecifically, the FTO 40 includes a vessel 41 filled with a matrix bedof PIM 42 (a small portion of the PIM matrix bed is illustrated). ThePIM may be, for example, a packed bed of heat resistant material, suchas ceramic balls or saddles. The matrix bed 42 is heated by introducinga heated medium 48 (for example, air or flue gases generated by a fuelgas burner or an electric resistance heater) through a heating inlet 49.

A reactable process stream 44 is delivered into the heated matrix bed tofacilitate an oxidation reaction. The reactable process stream 44 isformed by combining a fume stream 51 containing an oxidizable material,an oxidizing agent stream 52 (such as air or oxygen), and asupplementary fuel gas stream 53 in a mixing device 50. The oxidizingagent 52 and supplementary fuel 51 promote oxidation of the fume stream51. After the reactable process stream 44 is formed, it is fed into afeed inlet 54 of the diptube 43. The diptube 43 is an open pipe ofsubstantially constant inner and outer diameter, which extends at leastpartially within the PIM matrix bed 42, as shown. The diptube 43 has aninlet 54 configured to receive the reactable process stream 44 and anoutlet 55 configured to deliver the air-combustible vapor mixture intothe matrix bed 42.

The reactable process stream 44 is directed into a region of the PIMmatrix bed 42 where the matrix bed temperature is sufficient to reactthe process stream to form at least one reaction wave 56. The chemicalsin the process stream typically remain substantially unreacted untilreaching the reaction wave 56, where a substantial portion of thechemicals are reacted over the wave length. Preferably, the non-planarreaction wave 56 is established entirely within the boundaries of thematrix bed. The reactable process stream 44 is reacted in the reactionwave 56 to produce the reacted process stream 46. The reacted processstream 46 is then directed through the matrix bed 42, through the voidspace 47, and out of the vessel through the exhaust outlet 45.

The location, stability, and size of the reaction wave 56 may becontrolled through a programmable control system 59. FIG. 1 shows acontrol system 59 that uses the readings from temperature sensors 58 toadjust the flow rates of the fume stream 51, oxidizing agent stream 52,and supplementary fuel gas stream 53. For example, if the temperaturedeclines in a specified location of the matrix bed, the control system59 is configured to send a signal, such as an electrical or pneumaticsignal, to a series of control valves (not shown) to increase the flowrate of supplemental fuel 53, or to decrease the flow rate of theoxidizing agent 52 added to the flameless thermal oxidizer in order toprevent migration of the wave further away from the exit of the diptube.Conversely, if the temperature increases in the non-planar reaction waveto an undesirable level, the control system 59 is configured to send asignal to a control valve (not shown) to decrease the flow rate ofsupplemental fuel 53 or increase the flow rate of the oxidizing agent 52added to the flameless thermal oxidizer in order to prevent the wavefrom migrating into the inside of the diptube.

The control system 59 is also configured to adjust the flow rates of thefume stream 51, oxidizing agent stream 52, and supplementary fuel gasstream 53 in order to limit or prevent flashback. Flashback is aphenomena which occurs when the flame speed of a flammable mixture offuel and air is greater than the local velocity profile of the flammablemixture in the presence of an ignition source.

The FTO 40 is not generally intended for use with a flammable gasmixture because it does not include provisions to contain flashback. Asdescribed above, the FTO includes provisions, i.e., the programmablecontrol system 59, for preventing flashback. In order to preventflashback, the mixture of the process gas stream 51, oxidizing agentstream 52 and supplementary fuel gas stream 53 is typically maintainedat least about five percentage points below the lower flammability limitand delivered into the matrix bed at a velocity that is slightly greaterthan the flame speed of the mixture.

FIG. 2 depicts an exemplary embodiment of a flameless thermal oxidizer(FTO) 140 shown schematically according to aspects of the invention. TheFTO 140 is similar to the FTO 40 shown in FIG. 1, however, the diptube43 and mixing device 50 of FIG. 1 are replaced with a diptube assembly10. Similar to the diptube 43 of FIG. 1, the diptube assembly 10 ispositioned at least partially within a PIM matrix bed 42 containedwithin the FTO vessel 41. The diptube assembly 10 may be sized to fitwithin the same space constraints of the FTO vessel 41 as the diptubeshown in FIG. 1.

According to an exemplary embodiment, the diptube assembly 10 generallycomprises an outer conduit 12, a fuel conduit 14 positioned within theouter conduit 12, a fuel plenum 16 positioned at the base of the fuelconduit 14, and a plurality of mixing conduits 18 (one shown) extendingthrough the fuel plenum 16. Only one mixing conduit 18 is shownthroughout the figures for the purpose of clarity.

According to one exemplary use of the FTO 140, a mixture 19 comprising afume stream and an oxidizing agent stream (e.g., oxygen or air) isintroduced through an inlet 20 provided near the top end of outerconduit 12. The fume stream and the oxidizing agent stream may either becombined at the inlet 20 of the outer conduit 12 or any other location.The mixture 19 travels within the annular space defined between theouter conduit 12 and the fuel conduit 14. The mixture 19 is ultimatelydistributed into the individual mixing conduits 18.

A supplementary fuel stream 15 (e.g., natural gas, propane, kerosene, or#2 fuel oil) is introduced through an inlet 13 of the fuel conduit 14.The fuel stream 15 travels along the fuel conduit 14 and is distributedinto a fuel plenum 16. The fuel plenum 16 is essentially a hollowcylinder defining a closed cylindrical region, through which theplurality of mixing conduits 18 are positioned. The fuel stream 15 andthe mixture 19 are isolated until they are combined together within theinterior of the mixing conduits 18 (one shown in FIG. 3 for clarity) toform reactable process stream 32, as best described in FIG. 5.

FIG. 3 is a detailed view of the lower end of the diptube assembly 10cross-section shown in FIG. 2, according to an exemplary embodiment ofthe invention. FIG. 3 depicts a cross section of the outer conduit 12,fuel conduit 14, fuel plenum 16 and mixing conduits 18 (one shown forthe purposes of clarity). The fuel plenum 16 is mounted to the interiorrevolved surface of outer conduit 12. The fuel plenum 16 may be welded,adhered or fastened, for example, to the interior surface of the outerconduit 12. The fuel plenum 16 comprises an upper barrier 23, a lowerbarrier 24, and a cylindrical ring 25 interposed between the barriers 23and 24. The components of the fuel plenum 16 are optionally weldedtogether.

The lower barrier 24 is a cylindrical disc having a series of holesformed therein for accommodating the mixing conduits 18, according to anexemplary embodiment of the invention. The mixing conduits 18 may bewelded to the lower barrier 24 to limit escapement of the fuel stream 15through the lower barrier 24.

The upper barrier 23 is a cylindrical disc having a series of holesformed therein for accommodating the outlet end 26 of the fuel conduit14 and the inlet end of each mixing conduit 18, as best shown in FIGS. 3and 4. FIG. 4 is a cross sectional view of the entire diptube assembly10 taken along the lines 4-4 of FIG. 2. The inlet end of each mixingconduit 18 is coupled to the upper barrier 23, and may be welded to theupper barrier 23 to limit or prevent introduction of the mixture 19 intothe fuel plenum 16. The outlet end 26 of the fuel conduit 14 is alsocoupled to the upper barrier 23, and may be welded to the upper barrier23 to limit introduction of the fuel stream 15 into the annular spacebetween the outer conduit 12 and the fuel conduit 14. Alternatively, itmay be desirous to permit some portion of fuel stream 15 to mix into theannular space between the outer conduit 12 and the fuel conduit 14.

FIG. 5 depicts a detailed view of the mixing conduit 18 shown in FIG. 3.According to one exemplary use of the invention, the supplementary fuelstream 15 travels along the length of fuel conduit 14 and is distributedthrough the outlet end 26 of the fuel conduit 14 and into the fuelplenum 16. As stated above, the outlet end 26 of the fuel conduit 14 ismounted to a cylindrical opening provided in the upper barrier 23. Thefuel stream 15 collects in the fuel plenum 16 and is ultimatelydistributed into the mixing conduits 18 through a series of openings orapertures 30 formed along the surface of the mixing conduits 18.

The apertures 30 are formed along the segment of each mixing conduit 18that is disposed between the upper and lower barriers 23 and 24, suchthat the fuel stream 15 within the fuel plenum 16 circulates into themixing conduits 18. As best shown in FIG. 5, the fuel stream 15 iscombined with the mixture 19 (comprising a fume stream and an optionaloxidizing agent stream) within the mixing conduits 18 to form reactableprocess stream 32. The reactable process stream 32 is ultimatelydelivered into the heated PIM matrix bed (not shown) through the outlet22 of each mixing conduit 18.

The mixing conduits 18 are tailored to deliver the reactable processstream 32 into the PIM matrix bed with sufficient local velocity tolimit or prevent a flashback. Flashbacks occur when the flame speed of aflammable mixture of fuel and air is greater than the local velocityprofile of the fuel and air mixture in the presence of an ignitionsource. Accordingly, the potential for flashback is substantiallyreduced by increasing the local velocity profile of the fuel and airmixture, and quickly distributing that mixture into the matrix bed.

Substantially increasing the velocity of the reactable process streamreduces the residence time for a fully integrated fuel-air mixturewithin the mixing conduits 18, which diminishes the potential foruncontrolled deflagration due to inventory minimization of potentiallycombustible gases. By delivering the reactable process stream 32 intothe matrix bed at a velocity sufficiently greater than its flame speed,the fuel-air mixture may be maintained at or near the lower flammabilitylimit of the mixture. Maintaining the fuel-air mixture at or near thelower flammability limit of the mixture minimizes FTO operational costsand maximizes the available capacity of the FTO vessel.

To meet those objectives, the number, position, cross-sectional area andlength of the mixing conduits 18, individually or in combination, aretailored to deliver the reactable process stream 32 into the PIM matrixbed with sufficient local velocity to limit or prevent a flashback.

According to one exemplary embodiment, the collective cross-sectionalarea of the mixing conduits 18 is less than both the cross-sectionalarea of the fuel conduit 14 and the effective cross-sectional area ofthe outer conduit 12. Constricting the flow path of the mixture 19through the mixing conduits 18 increases its local velocity, such thatthe local velocity of the mixture 19 (as it forms reactable processstream 32) is greater than its flame speed.

According to the exemplary embodiment, the collective cross-sectionalarea of the mixing conduits 18 is the sum of the interiorcross-sectional areas of all of the mixing conduits 18. The effectivecross-sectional area of the outer conduit 12 is the difference betweenthe interior cross-sectional area of the outer conduit 12 and the outercross-sectional area of the fuel conduit 14, because the mixture 19flows in the annular area defined between the outer conduit 12 and thefuel conduit 14.

According to the exemplary embodiment, the inner diameter of each mixingconduit 18 may be from about 0.5 to about 3 inches, for example. Themixing conduit 10 may optionally include forty-two (42) mixing conduits18. The inner diameter of the outer conduit 12 may be from about 6 toabout 60 inches, for example. The inner diameter of the fuel conduit 14that is positioned within the outer conduit may be from about 1 inch toabout 6 inches, for example. A ratio of the effective cross-sectionalarea of the outer conduit 12 to the collective cross-sectional of themixing conduits 18 is between about 2.5:1 and 6:1.

The velocity of the reactable process stream 32 increases as it travelsthrough each mixing conduit 18. The velocity of the reactable processstream 32 may be between about 50 feet/second to about 250 ft/second asit travels through each mixing conduit 18. Accordingly, the length ofeach mixing conduit 18 is maintained at a minimum such that the localvelocity of the reactable process stream 32 is greater than its flamespeed. According to one exemplary embodiment, for example, the length ofeach mixing conduit 18 may be about 36 inches. Minimizing the flow pathof the reactable process stream 32 reduces the potential for substantialdeceleration of the mixture 32 within each mixing conduit 18.

According to one exemplary embodiment, the distance separating theoutlet of each mixing conduit 18 and the PIM of the matrix bed 42 isalso maintained at a minimum to limit or prevent substantialdeceleration of the reactable process stream 32 upon exiting the mixingconduit 18, but prior to reaching the PIM matrix bed 42. The outlet ofeach mixing conduit 18 may be positioned within the matrix bed 42, if sodesired.

Because the reactable process stream 32 is delivered directly into thematrix bed 42 through the mixing conduits 18 at a local velocity greaterthan its flame speed, the equivalence ratio of the reactable processstream 32 may be maintained between a range of about 0.5:1 to about0.8:1, which is within the flammability limits for natural gas mixtures.Specifically, each mixing conduit 18 is configured to premix the fuelstream 15 and the mixture 19 (containing air) at an equivalence ratio ofbetween a range of about 0.5:1 to about 0.8:1.

According to another aspect of the invention, the equivalence ratio ofthe reactable process stream 32 may be maintained above the lowerflammability limit for natural gas mixtures, i.e., above 0.4:1. Broadlystated, the equivalence ratio of the reactable process stream 32 may bemaintained between a range of about 0.09:1 to about 4:1. The equivalenceratio of the reactable process stream 32 may be maintained at or abovethe lower flammability limit for natural gas mixtures, i.e., above0.4:1, by virtue of the high local velocity of the process stream 32(due to the constricted-flow through the mixing conduits 18) and theclose proximity of the outlet of the mixing conduits 18 to the matrixbed 42.

For the purpose of comparison, the equivalence ratio in a FTO, such asthe FTO shown in FIG. 1, is maintained at about 0.35:1, which is wellbelow the lower flammability limit for natural gas mixtures. As statedpreviously, the equivalence ratio is maintained below the lowerflammability limit in a FTO to prevent or reduce the risk of flashbackin addition to other operational benefits. More particularly, becausethe air and fuel are combined at either the inlet end of a diptube or ina mixing device (e.g. item 50 of FIG. 1) in a FTO, flashback couldpotentially occur if the fuel-air mixture was maintained equal to orgreater than its lower flammability limit. For that reason, in FTO's thefuel-air mixture is maintained at least about five percentage pointsbelow its lower flammability limit to prevent flashback.

Maintaining the fuel-air mixture at least about five percentage pointsbelow its lower flammability limit may facilitate excessive fuelconsumption and overly conservative vessel sizing criteria. Moreparticularly, less supplemental fuel is required to oxidize a processstream 32 having an equivalence ratio greater than the lowerflammability limit (i.e., 0.4:1) because less dilution air is requiredto maintain a low equivalence ratio. Thus, the cost of fuel consumed bythe FTO 140 is significantly lower than that of a FTO, which is directlyattributable to the diptube assembly 10 of the FTO 140.

Referring now to FIG. 6B, each mixing conduit 18 includes a series ofapertures 30 for distributing the fuel stream 15 with the mixture 19(containing air) at greater equivalence ratios than about 0.4:1.According to one exemplary embodiment, each mixing conduit 18 optionallyincludes two rows of four apertures 30. A detailed view of the top rowof apertures 30 is shown in FIG. 6A. The top and bottom rows eachoptionally include four apertures positioned at 0°, 90°, 180°, and 270°,as shown in FIG. 6A. The adjacent apertures 30 are separated by 90° topromote uniform distribution of the fuel stream 15 within each mixingtube 18.

In another exemplary embodiment of the mixing tube shown in FIG. 6B, theapertures are positioned at 45°, 135°, 225°, and 315°. To promoteuniform distribution of the fuel stream 15 within each mixing tube 18,the top row of apertures may be positioned at 0°, 90°, 180°, and 270°,and the bottom row of apertures may be positioned at 45°, 135°, 225°,and 315°, respectively. In such an exemplary embodiment, the adjacentapertures 30 of both the top and bottom rows are separated by ninetydegrees with respect to each other, and the apertures of the top row areseparated by 45 degrees from the nearest apertures 30 of the bottom row.It should be understood that the mixing conduits 18 may incorporate anynumber of apertures 30. Moreover, the apertures 30 may be positioned atany angle with respect to each other to serve any specific purpose.

Referring back to FIG. 5, each aperture 30 is disposed through the wallof the mixing tube at an angle “A.” The angle “A” may be approximately45°, for example. The apertures 30 are positioned at angle “A” to directthe fuel stream 15 toward the outlet 22 of the mixing tube 18. Thediameter of the aperture 30 is inversely proportional to the velocity ofthe fuel stream within the mixing tube 18, i.e., the velocity of thefuel stream distributed through the aperture 30 increases as thediameter of the aperture decreases, and vice versa. The diameter of eachaperture 30 also impacts the required equivalence ratio and total heatinput. The aperture size may vary widely. By way of non-limitingexample, the diameter of each aperture 30 may range from about 0.02inches to about 0.25 inches.

While exemplary embodiments of the invention have been shown anddescribed herein, it will be understood that such embodiments areprovided by way of example only. Numerous variations, changes andsubstitutions will occur to those skilled in the art without departingfrom the spirit of the invention. For example, the fuel stream 15 may bedistributed through the inlet of each mixing conduit 18 and the mixture19 may be distributed into the apertures 30 of each mixing conduit 18 toachieve a similar effect. Moreover, in lieu of the fuel plenum 16, thesupplementary fuel stream 15 may be directly distributed into the mixingconduits 18 through a series of injectors, tubes or conduits (not shown)to achieve a similar effect. Also, the fuel stream 15 may be distributeddirectly into the fuel plenum 16 and the fuel conduit 14 may be omitted.It should be also understood that the conduits 12, 14, and 18 are notlimited to a circular cross-sectional shape, as other cross-sectionalshapes are envisioned, such as square, rectangular, and so forth.

Accordingly, it is intended that the appended claims cover all suchvariations as fall within the spirit and scope of the invention.

1. A diptube assembly for a flameless thermal oxidizer having a matrixbed of media comprising: a fuel conduit at least partially positionedwithin the matrix bed for delivering fuel; an oxidizing agent conduit atleast partially positioned within the matrix bed for deliveringoxidizing agents, wherein said oxidizing agent conduit is separate fromsaid fuel conduit; at least one mixing conduit positioned within thematrix bed and configured to receive fuel from said fuel conduit and theoxidizing agent from said oxidizing agent conduit, wherein said mixingconduit is positioned to deliver the combination of fuel and oxidizingagents into the matrix bed of media.
 2. The diptube assembly of claim 1further comprising a fuel plenum, wherein said fuel conduit ispositioned to deliver fuel into said fuel plenum.
 3. The diptubeassembly of claim 2 wherein at least a portion of said mixing conduit ispositioned within said fuel plenum.
 4. The diptube assembly of claim 3further comprising at least one aperture formed in said at least aportion of the mixing conduit positioned within said fuel plenum,wherein fuel from the fuel plenum is delivered through said apertureinto an interior region of said mixing conduit.
 5. The diptube assemblyof claim 4 wherein the mixing conduit includes a plurality of aperturespositioned to distribute fuel from said fuel plenum into the interiorregion of said mixing conduit.
 6. The diptube assembly of claim 1wherein the mixing conduit is configured to mix the fuel and theoxidizing agents at an oxidizing agent to fuel equivalence ratio ofbetween about 0.5:1 to about 0.8:1.
 7. The diptube assembly of claim 1wherein the mixing conduit is configured to mix the fuel and theoxidizing agents at an oxidizing agent to fuel equivalence ratio in arange of between about 0.09:1 to about 4:1.
 8. The diptube assembly ofclaim 1 further comprising a plurality of mixing conduits configured toreceive fuel from said fuel conduit and an oxidizing agent from saidoxidizing agent conduit and deliver the combination of fuel and theoxidizing agent into the matrix bed of media.
 9. The diptube assembly ofclaim 1, wherein a ratio of the effective cross-sectional area of theoxidizing agent conduit to the collective cross-sectional area of theplurality of mixing conduits is between about 2.5:1 to about 6:1. 10.The diptube assembly of claim 1 wherein an outlet of said mixing conduitis positioned adjacent to the matrix bed to deliver the combination offuel and oxidizing agents directly into the matrix bed.
 11. A diptubeassembly for a flameless thermal oxidizer having a matrix bed of mediacomprising: a fuel conduit for carrying fuel at least partiallypositioned within the matrix bed; a fuel plenum positioned within thematrix bed being configured to receive fuel from said fuel conduit; anoxidizing agent conduit for delivering oxidizing agents into at leastone mixing conduit, wherein at least a portion of said mixing conduit ispositioned within said fuel plenum; and said at least a portion of saidmixing conduit includes at least one aperture formed in a surfacethereof, wherein fuel from said fuel plenum is delivered into saidmixing conduit through said aperture, wherein a combination of fuel andoxidizing agents are delivered through said mixing conduit into thematrix bed of media of the flameless thermal oxidizer.
 12. The diptubeassembly of claim 11 further comprising a plurality of mixing conduitsconfigured to receive fuel from the fuel conduit and oxidizing agentsfrom said oxidizing agent conduit.
 13. The diptube assembly of claim 11wherein an outlet of said mixing conduit is positioned adjacent to thematrix bed to deliver the combination of fuel and oxidizing agentsdirectly into the matrix bed.
 14. The diptube assembly of claim 11wherein said mixing conduit comprises two rows of apertures that areeach positioned to evenly and uniformly distribute fuel into an interiorof said mixing conduit.
 15. The diptube assembly of claim 11 whereinsaid fuel conduit is positioned within said oxidizing agent conduit. 16.The diptube assembly of claim 11 wherein a fume stream is delivered intosaid mixing conduit through said oxidizing agent conduit.
 17. Aflameless thermal oxidizer comprising: a vessel; a matrix bed of mediacontained within an interior of said vessel; and a diptube assembly atleast partially positioned within said matrix bed including: a fuelconduit for carrying fuel at least partially positioned within saidmatrix bed; an oxidizing agent conduit for carrying oxidizing agents atleast partially positioned within said matrix bed; at least one mixingconduit at least partially positioned within said matrix bed beingconfigured to receive and combine fuel from the fuel conduit andoxidizing agents from the oxidizing agent conduit and to deliver thecombination of fuel and oxidizing agents into the matrix bed of media.18. In a flameless thermal oxidizer having a vessel configured tocontain a matrix bed of media, and a fuel conduit and an oxidizing agentconduit each extending into an interior of the vessel at least partiallywithin the matrix bed of media, a method of delivering fuel andoxidizing agents into the vessel comprising the steps of: distributingfuel through the fuel conduit; distributing oxidizing agents through themixing conduit; and combining the fuel and the oxidizing agent in amixing conduit.
 19. The method of claim 18 further comprising the stepof delivering fuel and oxidizing agents within the mixing conduit intothe matrix bed of media.
 20. The method of claim 18 wherein thecombining step comprises distributing oxidizing agents into the interiorof the mixing conduit through an inlet of the mixing conduit, anddistributing fuel into the interior of the mixing conduit through anaperture formed in the mixing conduit.